Machining centers may seek validation that a cutting tool used within the machining center has stopped rotating before the operator is able to breach the machining center's enclosure. For example, some machining centers have doors that can only be opened when the cutting tool is no longer rotating.
Conventionally, a machine control system is wired to the cutting tool, in the form of an electric spindle, to power the tool. The machine control system also controls the accessibility of the enclosure. Therefore, when the electric spindle is receiving power, a door latch is closed. When the electric spindle is no longer receiving power, the latch can be disengaged and the door can be opened by an operator.
However, there can be a problem when operating spindles, linear axis, or live tools, which are not powered directly through the machine control system, because current machine control systems may be unable to sufficiently determine the tool's operating condition.